Protective body for ingot mold



Dec. 12, 1961 G. WIESNER 3,012,296

PROTECTIVE BODY FOR INGO'I MOLD Filed Sept. 28, 1959 Jnvenfor:

GUNTHER WIESNER AGENT United States Patent Ofiice 3,912,295 Patented Dec. 12, 1961 3,012,296 PROTECTIVE BODY FOR INGOT MOLD Giinther Wiesner, Kurfurstenstrasse 61, Essen, Germany Filed Sept. 28, 1959, Ser. No. 842,996 Claims priority, application Germany Sept. 29, 1958 9 Claims. (Cl. 22-147) My present invention relates to ingot molds and, more particularly, to protective bodies adapted to be placed in or on such molds to control the solidification of the molten mass therein.

In the processing of metals and especially in the manufacture of steel and steel products, wherein molten metal is poured into a mold and stripped therefrom for further processing in the form of a hot solidified ingot (e.g. by rolling, stamping, forging and the like), it is desirable to cover the head of the ingot by a so-called hot top in order to reduce the heat radiated from the melt, to protect the upper surface of the ingot against impurities and to limit the contact of the surrounding atmosphere with this surface.

Plugs and inserts hitherto produced to serve as hot-top covers and the like have been composed either completely of refractory materials, thus making the cover heavy and unwieldy, or of a combustible carbonaceous light-weight material such as charcoal or coke admixed with a quantity of sawdust and held together by a suitable binder. Such mold accessories have, upon contact with the poured metal, reacted with the hot melt by introducing dissolved carbon into the ingot mass along the upper surface thereof, thereby resulting in a weakened product. To inhibit carbonization, mineral carbonates were added to the combustible mixture. These carbonates, however, decomposed to form carbon dioxide which either dissolved in the melt or was reduced to produce soluble carbon. Other combustibles were used with similar effects. Furthermore, in order to limit the diffusion of undesirable gases such as oxygen toward the melt from the surrounding atmosphere and the dissolution thereof in the melt, the porous inserts and covers of either the refractory or the combustible type were provided with impermeable protective layers or coatings which, however, were expensive to apply and, often, prone to heat damage.

It is therefore an object of the present invention to provide a light-weight accessory for ingot molds adapted to withstand high temperatures and to resist interaction with the melt.

In accordance with a feature of my invention I form a mold accessory of the character described, e.g. in the shape of a slab or as a laminate of several slabs, from comminuted cellulosic material such as sawdust or wood chips admixed with a quantity of a highly comminuted mineral such as a silicate or an aluminate, using waterglass as a binder. The Waterglass serves the dual function of rendering the slab impenetrable to gases and making the mixture incombustible. The surface of the slab in contact with the melt has the high heat resistivity characteristic of waterglass and substantially prevents any reaction between the other components of the mixture and the melt. Additional protective layers are thus unnecessary. The most favorable proportions of the components constituting the slab have been found to be60 to 95% by volume of wood chips, sawdust or the like along with to 40% by volume of mineral matter.

According to another feature of the invention, I make each slab of such limited thickness (preferably not more than 50 mm.) as to enable its ready penetration by bolts or pins for securing it to the ingot mold.

The above and additional objects, features and advantages of the invention will become more readily apparent from the following description, reference being made to the accompanying drawing in which the sole figure is a 2 somewhat schematic illustration of an ingot mold provided with a hot-top cover embodying my invention.

In the figure I show, somewhat schematically, an ingot mold 1 comprising a conventional refractory lining 2 at thelower part thereof and walls 13, hinged at 13', surrounding the so-called hot top. A ferrous melt 3 fills the mold 1. Laminated liners 14, secured by bolts 12 to the walls 13 of the hot top, and a similarly constructed cover 4, having a handle 5 for ease in positioning it on the mold from above, are made of a light-weight incombustible mixture according to the invention. The cover 4 comprises a plurality of slabs 4a, 4b, 4c, 4d fastened together by several pins 8, only one of which is shown. Cover 4 may be secured to the mold top by steel pins 8', readily driven through the thin top slab 4d by pneumatic or explosive pin-setting devices known per se, which connect its overhanging flange portions with the mold'top 13, 14. The cover may also be reinforced by sheet-metal strips (not shown) at the points of attachment to the mold, or elsewhere.

Example A composition suitable for the cover 4 and the liners 14 is prepared by combining a mixture containing between 5 and 20% by volume of finely ground fire clay and to by volume of sawdust, wood meal, wood chips or the like with a quantity of waterglass equal to that capable of adsorption by the mixture. The composition is then pressed or otherwise for-med into a slab or plate and baked in an oven at temperatures of approximately 200 C. to dry the slab. The latter may be hardened with the aid of carbon dioxide in addition to the baking operation or in place thereof. The slab produced as described above will be found to have sufiicient strength for the purposes mentioned at thicknesses as low as 50 mm. or less.

Slabs made in accordance with my invention, used as liners, inserts, plugs and so forth as described above, will not radiate heat toward the mold but will remain black on the mold side even after prolonged contact with the melt, thus throughout the entire teeming and hardening process. At the same time any diffusion of atmospheric gases through the slabs toward the melt is positively prevented by the impermeability of the waterglass-impregnated cellulosic-ceramic mixture.

The invention described admits of many modifications and variations, readily apparent to persons skilled in the art, which are intended to be included within the spirit and scope of my invention except as further limited by the appended claims. I

I claim:

1. A process for making a protective body for an ingot mold, comprising the steps of mixing together comminuted cellulosic and comminuted ceramic materials, with the cellulosic material predominating in a proportion of at least 60% by volume, and impregnating the mixture with waterglass as a binder in sufi'icient quantity to render said mixture incombustible and gas-impermeable.

2. A process for making a protective body for an ingot mold, comprising the steps of mixing together at least 60% by volume of comminuted cellulosic material and at most 40% by volume of comminuted fire clay, and impregnating the mixture with waterglass as a binder in sufficient quantity to render said mixture incombustible and gas-impermeable.

3. A process for making a protective body for an ingot mold, comprising the steps of mixing together 80 to 95% by volume of comminuted Wood fragments and 20 to 5% by volume of finely ground fire clay, and impregnating the mixture with waterglass as a binder in sufiicient quantity to render said mixture incombustible and gas-impermeable.

ture of comminuted cellulosic and comminuted ceramic materials impregnated with waterglass, the cellulosic material predominating in a proportion of-at least 60% by volume. I

5. An accessory according to claim 4 wherein said body is in the form of a slab.

6. An accessory according to claim 4 wherein said body is in the form of a plurality .of slabs mechanically laminated together.

I 7. An accessory according to claim 4 wherein said body has a maximum thickness of substantially 50 mm.

8. In combination, an ingot mold and a refractory member attached to said mold, said member consisting of a body formed from an incombustible and gas-impermeable mixture of comminuted cellulosic and comminuted ceramic materials impregnated with waterglass, the cellulosic material predominating in a proportion of at least 60% by volume. a

References Cited in the file of this patent UNITED STATES PATENTS 2,156,980 Gr'oninger May 2, 1939 2,229,507 Johnston Jan. 21, 1941 2,282,248 Rowe May 5, 1942 2,846,741 Whitacre Aug. 12, 1958 2,869,191 Cooper et al Jan. 20, 1959 2,873,492 Vallak Feb. 17, 1959 2,890,504 Daley et a1 June 16, 1959 FOREIGN PATENTS 563,752 Canada Sept. 23, 1958 

